SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are cryptographic protocols that provide secure communication over a computer network. Here's a breakdown of how they work and their purpose:

SSL and TLS Basics:

• SSL: An older protocol developed in the mid-1990s for encrypting connections between clients (such as web browsers) and servers. SSL has largely been replaced by TLS due to various vulnerabilities.
• TLS: A more secure and updated version of SSL. Most references to SSL today actually refer to TLS, as TLS is the current standard used to establish secure connections.

Purpose:

The primary purpose of SSL/TLS is to encrypt the data being transferred between the client and the server to ensure it cannot be read or tampered with by attackers. It also helps to:

• Authenticate the server (and optionally the client) to ensure you're communicating with the correct party.
• Maintain data integrity, ensuring that data has not been altered during transmission.

How SSL/TLS Works:

1. Handshake: When a client connects to a server, the SSL/TLS handshake process begins. This involves exchanging cryptographic information to establish the secure connection.
2. Encryption: The server sends its SSL/TLS certificate to the client, which contains the server's public key. The client generates a session key, encrypts it with the server's public key, and sends it back. Both parties then use this session key for encrypting and decrypting the data exchanged during the session.
3. Data Transfer: Once the connection is established, all data is encrypted with symmetric encryption using the session key. This ensures that even if the data is intercepted, it cannot be read without the session key.
4. Termination: The secure connection is closed when either the client or server terminates the session.

Why It's Important:

SSL/TLS provides:

• Confidentiality: Data is encrypted, so only the intended recipient can decrypt and read it.
• Integrity: Ensures that the data sent over the connection is not tampered with or altered.
• Authentication: Verifies the identity of the server, preventing "man-in-the-middle" attacks where an attacker intercepts or alters the communication.

Modern browsers and services use TLS (usually versions TLS 1.2 and TLS 1.3) for secure communication, such as HTTPS (HTTP Secure), which is essentially HTTP over TLS.